Mesostigmata

(invertebrate zoology) The mites, a suborder of the Acarina characterized by a single pair of breathing pores (stigmata) that are located laterally in the middle of the idiosoma between the second and third, or third and fourth, legs.

A suborder of the Acarina, commonly referred to as the mites. Mesostigmata are characterized by a single pair of breathing pores, or stigmata, located laterally in the middle of the idiosoma between the second and third, or third and fourth, legs. A two- or three-tined palpal claw and a tritosternum, which is located ventrally on the idiosoma just behind the gnathosoma, are also characteristic for most mesostigmatid mites. The Mesostigmata range from less than 0.008 in. (0.2 mm) to more than 0.16 in. (4 mm) in length and are cosmopolitan in distribution.

Mesostigmatid mites generally pass through an egg stage, a six-legged larval stage, two eight-legged nymphal stages, and an adult stage. In one group of these mites there is a nymphal stage which serves as a means of dispersal for the species. These nymphs attach themselves to insects and other arthropods by means of an anal pedicel and “hitchhike” to the next suitable habitat.

Many of the Mesostigmata are predacious on other small arthropods or are scavengers and fungus-feeders that make up an important segment of the soil fauna. Some members of the family Phytoseiidae are beneficial to humans as predators of the destructive spider mites, Tetranychidae. Other forms are parasitic on insects and other invertebrates. Terrestrial arthropods are the only invertebrate hosts affected by mesostigmatid mites. As a rule, phoresy is the predominant reason for the association. Vertebrate hosts are restricted to mammals, birds, and reptiles. The Mesostigmata that parasitize them are of two main sorts: They are either internal parasites of the respiratory passages, or they are ectoparasitic nidicoles; that is, they reproduce in the nests of their hosts. See also Phoresy.